Facsimile-telegraph apparatus.



No. 759,701. PATBNTED MAY 1o, 1904. E. LGRUHN. FACSIMILE T'ELEGRAPH MPARATUS.

APPLICATION FILED NOV. 21, 1902.

N0 MODEL.

| |s irene cn'. Pnoramwn.. wAsHmc-mn n c fly 2 muv.. dm/uml' UNITED STATES Patented May 10, 1904# PATENT OEEICE.

ERNST KARL GRUHN, OF DRESDEN GERMANY, ASSIGNOR TO TELAU- TOGRAPH, GESELLSGHAEI MIT BESCHRAENKTER HAETUNG', OE

DRESDEN, GERMANY.

FACSIMILE-TELEGRAPH APPARATUS.

SPECIFICATION forming part or' Letters Patent No. 759,701, dated May 10, 1904.

Application filed November 2l, 1902. Serial No. 132,298. (No model.) I

To n/ZZ whom, '1125 nen/y concern:

Be it known that I, EnNs'r KARL Gnunn, a subject of the King' oi Prussia, German Emperor, residing at Dresden, Saxony, Germany, have invented certain new and useful Improvements in or Relating to Facsimile-Telegraph Apparatus, of which the following' is a speciiication.

r1`he known transmitting mechanism vFor Yfacsimile tclegraphic apparatus of which the 'function is based upon thc principle of decomposing' the motion of the stylus into orthogonal coordinates by levers connected with the stylus and passing over and in contact with resistances (or by levers or the like connected with the stylus and operating' rotary contacts or resistances) do not effect a precise decomposition, but merely an approximately exact decomposition yof the motion of the stylus. The inexactness is due to the fact that during' the motion of the writing-stylus alongl one coordination-axis an oscillation oi" the lover of the other coordination-axis is et'- 't'ected, which oscillation owing to the deviation between the arc and subtense causes a displacement of the leverfulcrum-. c., an alteration in the length of the lever or drawing means. r1`hus while during the motion of the writing-stylus parallel to one axis the resistance in the second lever system should not vary, owing' to the motion of the writingstylus in the direction of the second axis being olf/IZ, nevertheless a variation ot' the rcsistance takes place in the letter system, whereby, oi` course, the reproduction of the motion of the stylus is also unfavorably infiuenced in every other direction of motion. The extent oi the error increases with the length or extent ot movement or' the lever or drawing means. 1f it is, however, attempted to render the amplitude oi' movement so small as to make the error negligible, inconvenient measurements would be obtained.

lt is the object of the present invention to dispense with the erroneous variations of the resistance, and this is etlected by the arrangement oi a curved contact-piece bearing and gliding" upon a resistance arranged along the path of motion or' the fulcrum-lever, which contact-piece is connected with the lever and S0 has such a curvature that the conse-quent displacementof the contact-piece during the oscillation ot the lever does not cause a Vdis-` placement oi' the contact-point upon the re- Sistance. such that the contact-point by the peculiar curvature of the contact-piece is displaced through the simultaneous oscillation by so much as it would advance by the displacement ot' the lever upon the contact, so thatin reality 60 it does not move 'from its position. From this suppression orf the error it results that the contact-point in each of the systems undergoes only the precise displacement upon the resistance which it should undergo owing' 65 to the corresponding' motion or the cordinates.

The invention is represented in two forms of construction in the accompanying' dravings, in whichm Figure 1 shows a top `plan view oiE the apparatus diagrammatically, the straight guide oi' the level' being' omitted for the sake oi clear-ness. Fig'. 3 is a lateral View showing only one system, and Fig'. 2 is a partial top 7 5 plan view or' the second construction.

lis the stylus, with which are connected two levers 2 and 2, with pivots Band 3 movable in straight guides 4L and il, placed at right angles to one another and carrying the contact- SO arcs 5 and .'31. As can be seen from a comparison ot' Figs. 1 and 2, the contact-arc is situated in the ii rst construction between pivot 3 (or Bn) and the stylus, while it is on the other side ot' the pivot in the other construction. 85 The contact-arcs glide upon the resistanccs 6 and 6, arranged beneath the straight pivotguide. The arrangement is the usual one for facsimile-telegraphs of this type, whereby by varying' the resistances 6 and 6IL the electric 90 phenomena in the long-distance branch conductors leading' to'the receiver are varied accordingly. In the following description the shape given to the contact-pieces will be more The shape of the contact-piece is 55 clearly defined. According to the above statements it is necessary to render the extent of displacement of the point of contact between the contact-arc and the resistance precisely equal to the motion performed by the point of the stylus in the direction of the motion of the corresponding component. Thus if the stylus describes, as shown in Fig. 1, an irregular curve p q the point of contact o should travel a distance b fr q. If the stylus moves from p toward the center of the writing plane, the point of contact should remain stationary. This case will first of all be analytically investigated. Assuming the writing -stylus moves straight from p to m, the fulcrum 3 of the lever will be moved back to the point t through the distance y. The vertex of the contact-arc will then be situated at the point e. The contact-arc therefore must have a determined curvature, so as to prevent the contactpoint from being displaced. The curvature will hereinafter be expressed in the t'orm of an equation. The curvature of the arc is a function of the angle a. Suppose the length of the lever-arm is Z and the distance 310:65. It follows that `Url-(3110; Smzl cos. a. Substituting the equivalent for (3m),

y:l (l-cos. a.)

Assuming' the distance .fr is the variable radius ot' the contact-arc, which varies according to the angle a,

Radius mra-yZa-Z (1 -cos. LY.)

In order to ind the distance through which the point e travels when the stylus passes along the curve 2J q, it should be imagined that the stylus moves in a straight line from p to fr and then from r to g. During the travel of the stylus from p to r the point c remains stationary according to the above equation. During the motion from 1 to q the angle Y does not vary, and the point o travels through a distance Z2, which, as can be easily seen, is equal to o q, as had to be proved. In case the contact-arc is on the opposite side of the pivot 3, Fig. 2, it has a different curvature, and the following equation prevails:

That I claim as my invention, and desire to secure by Letters Patent, is#

l. In a transmitting device for facsimile telegraphic apparatus wherein the motion of the stylus is decomposed into orthogonal cordinates to eiect avariation in the resistance of the line conductors, the combination with a stylus, a lever connected therewith and mounted to have a bodily 'as well as an oscillatory movement and a fixed resistance body, of a contact moving in unison with the lever and cooperating with the resistance body, said contact having a contact-surface corresponding in shape to a path described on the contact by a Xed point on the resistance body when the stylus is moved transversely in a right line and whereby when so moved the electrical resistance will not be varied; substantially as described.

2. In a transmitting device for facsimile telegrapliic apparatus wherein the motion of the stylus is decomposed into orthogonal cordinates to eect a variation in the'resistance of the line conductors, the combination with a stylus, two levers connected therewith and mounted on axes having a movement in orthogonal lines with respect to each other and fixed resistance bodies extending in the direction of motion of the lever-axes, of contacts moving in unison with the levers and having contact-surfaces engaging the resistances and corresponding in shape to paths described on the contacts by xed points on the resistance bodies when the stylus is moved on the orthogonal line of the axis of the opposite lever to that with which the contact is connected; substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ERNST KARL GRUHN.

Vitnesses:

KARL GRIMSBY, OTTO XVOLFF. 

